Measurement and correlation of infinite dilution partition coefficients of aromatic compounds in the ionic liquid 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim][PF6])–CO2 system at temperatures from 313 to 353 K and at pressures up to 16 MPa

Infinite dilution partition coefficients of benzene, toluene, chlorobenzene and naphthalene in the ionic liquid, 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim][PF6])–CO2 system were measured with a chromatographic technique. Partition coefficients for each solute increased with increasing pressure and had the trend of Kbenzene∞>Ktoluene∞>Kchlorobenzene∞>Knaphthalene∞ at a given temperature. At pressures above 12 MPa, Knaphthalene∞ became one order in magnitude smaller than that of the other components, which is attributed to the π–π interactions between naphthalene and the imidazolium group of the ionic liquid. The Sanchez–Lacombe equation of state was found to provide adequate correlation of the data and their temperature and pressure trends.